Change readahead to 1024.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Signed-off-by: Hieu Phan <aznrice2k4@gmail.com>

Conflicts:
	include/linux/mm.h

Change-Id: Id060c05e544c074aea4b12f21d236600cf4ab6bb